This invention relates to a method and a device for treatment of filament yarn in a yarn channel of a nozzle with a supply of blowing medium into the yarn channel.
Treatment of continuous filament yarn has mainly two functions. First, a textile character and technical textile properties are to be imparted to the yarn which is produced from filaments synthesized industrially. Secondly, the yarn is treated from the standpoint of specific quality features for further processing and/or for the end product. To some extent, grades of yarn must be manufactured that are not necessary and cannot be achieved with products produced from natural fibers. The fields of application are in industrial processing of textiles, e.g., for the construction sector, the automotive sector as well as for carpet production and for special textile products for use in the sports and leisure industries. Furthermore, spun yarn is to be treated for the best possible industrial processing by applying of certain preparations, and the processing operation is to be optimized for yarns and fabrics. Optimization in this sense also includes maintaining or increasing certain quality criteria and lowering production costs, even with respect to downtime along the entire processing route.
Various treatments such as preparation and finishing of yarn by way of yarn treatment nozzles are an important part of filament spinning. The change in structure from a smooth yarn to a textured or interlaced yarn is achieved by means of mechanical air forces. In the case of texturing, a textile character is to be imparted to the smooth yarn. Small loops in the filaments are produced with a supersonic flow, and thus a greater volume is achieved over the entire yarn. In interlacing, knots are formed in the yarn at short intervals, increasing cohesion of the yarn and imparting more stable running of the yarn in processing and in spooling. Air treatment nozzles are used to improve the structure of a yarn. One very demanding process is the improvement in quality by treatment with superheated steam, e.g., for relaxing a yarn as part of a drawing operation or after a previous process measure. In all cases, the nozzle bodies are made of a highly wear-resistant material, because otherwise their lifetime would be too short. The preparation step is a not insignificant source of problems for yarn treatment nozzles. In this process, yarn is provided with protective substances immediately after the spinning operation or after production of individual filaments. These protective substances should be of assistance in subsequent processing. The substances used for this preparation step result in an oily lubricant property, so that the sliding friction of the yarn remains as low as possible over the entire path of processing, the risk of damage and yarn breakage is reduced, and abrasion on the friction surfaces of the conveyance and processing installations can be minimized. However, there are a number of other factors such as static charge buildup on which the preparation or preparation agent can have a positive influence. Another field of application is for protection of yarn from fungal attack during storage times between the various processing stages.
The drawing operation is another very important process step for filament yarn. After filaments leave the spinnerets, the yarns formed from them must be drawn. This drawing presupposes that the yarn is more or less smooth, although that is no longer the case when processing a textured yarn. In a great many applications, there is a need for imparting a minimal interconnection to the yarn. However, this interconnection may only be intense enough so that it does not have a negative effect on downstream processing operations. It is known that an intermingling nozzle can be arranged downstream from the site of application of preparation agents in a spinning operation. In this case, only very weak knots are formed in the yarn, or even better, only the beginnings of knots are formed to stabilize the transport operations which follow directly. One disadvantage here is finding optimum conditions or an optimum compromise between no knots at all and just the beginnings of knots. The intermingling nozzles known so far are characterized by poor utilization of the air treatment or a weak eddy formation, especially with a relatively low pressure of the processing air. In practice, the uniformity and constancy of the resulting yarn structure often suffer. In the state of the art there is no stable yarn treatment option or a corresponding device which produces enough filament interconnection that calm and stable yarn running is assured without any negative effects on downstream procedures or process stages or with respect to structural changes.
German Patent 41 02 790 describes a special problem in regard to false twist crimping machines and proposes a delivery nozzle. To this end, the delivery air is blown into the nozzle channel at an angle of 20xc2x0 to the direction of yarn travel, for example. In the case of a delivery effect almost exclusively, the yarn remains almost unchanged. U.S. Pat. No. 4,214,352 proposes a texturing nozzle for production of a looped yarn. An angle of approx. 45xc2x0 for introduction is mentioned.
The object of this invention was to develop a method as well as yarn treatment nozzles which would permit prebonding of the yarn interconnection, in particular with the greatest possible constancy of a gentle structural operation. The goal was to produce the interconnection even at the highest speeds of yarn transport, e.g., at speeds of 3000-7000 m/min, directly downstream from the spinnerets and in direct conjunction with the application of preparation agents. Part of the object of this invention was to improve the situation for treatment of yarn from the standpoint of preparation agents, productivity, especially quality, even at the highest speeds.
The method according to this invention is characterized in that the blowing medium is directed into the yarn channel somewhat in the direction of thread travel and at an angle of introduction with an angle deviation xcex1 from the perpendicular to the direction of thread travel, said angle deviation being greater than 15xc2x0 but less than 45xc2x0, with the filaments of the prepared yarn being blended and slightly crossed without producing knots.
The device according to this invention is characterized in that the device is designed as a migration nozzle having a compressed air feed channel into the yarn channel, said compressed air feed channel being aimed in the direction of yarn travel and arranged in the yarn channel with an angle deviation greater than 15xc2x0 but less than 45xc2x0 from a perpendicular to the direction of yarn travel.
This invention also relates to the use of this device for thorough mixing and uniform distribution of preparation agents on filament yarn, whereby the filaments are joined to form a slightly crossed but knot-free yarn, and the preparation agent is at the same time distributed optimally over the entire yarn.
This invention permits a large number of especially advantageous embodiments. In this regard, reference is made to claims 2 through 10 and 12 through 16.
Practice has shown that with an increase in yarn transport speed, namely to more than 3500 m/min in the case of polyester, for example, more than 3000 m/min in the case of polypropylene and more than 4200 m/min in the case of polyamide, thread running becomes unstable and erratic despite the preparation. This instability increases further with any further increase in spinning yarn speed. This becomes problematical in the case of higher multi-end spinning positions. This is true in particular of deflection rollers and drawing rollers in pre-oriented POY and finished-oriented FOY as well as fully drawn FDY spinning operations. Another factor is that a progressively smaller separation between adjacent yarn runs is desired, not least of all for reasons pertaining to mechanical engineering and the process technology, so that with the same machine depth which would previously accommodate four yarn runs, the desired goal today is eight to ten. With a smaller separation, there is an increased risk of skipping of filaments from adjacent yarn runs, which could then immediately cause a thread break. Not least of all for ecological reasons but also for economic reasons, it is impossible to increase the application of preparation agents to an unlimited extent through contact with the preparation lips accordingly.
All experiments so far have shown that the range up to 15xc2x0 represents a barrier for the angle of introduction of blowing air into the yarn channel or on the longitudinal middle axis LM of an intermingling nozzle. In most cases the air jet is directed at right angles onto the longitudinal middle axis in the case of intermingling nozzles, to produce two uniform eddies in the yarn channel. All experience so far has shown that the greater the inclination of the direction of the blowing air, e.g., in the range of about 10xc2x0 to approximately 15xc2x0 to a perpendicular line with respect to the yarn run, the greater the conveyance component of the air and thus the more the intermingling nozzle will lose its actual function, namely that of producing intermingling knots. Therefore, in those cases in which a certain air treatment was sought in the manner of the intermingling nozzles but without forming knots in the yarn, it seemed obvious to use an intermingling nozzle from the state of the art but to simply lower the air pressure until, for lack of energy, the compressed air could no longer form knots. One disadvantage of this was that the reproducibility of the results left much to be desired.
Systematic experimental series with this novel invention have surprisingly shown that new effects occur with a suitable adjustment of the blowing air pressure in the range of angles of introduction of more than 15xc2x0, namely there is a slight crossing of filaments with a corresponding mixing effect. The actual surprise found in our own experiments was that in the case of prior application of preparation agent to the yarn, this preparation agent would be optimally distributed on the yarn or the individual filaments and in particular the effect of the preparation agent would be significantly greater even with a reduction of 5% to 20% in the amount of preparation agent in comparison with the known practice. Smooth running, stability and a greater operating reliability can be achieved with this new solution. Thus, in many cases this makes it possible to save on preparation agent in the amount of 10-20% or more. There are many possible applications. It was very soon found that the effect of slight crossing would not interfere with any of the downstream treatment stages, e.g., neither drawing nor production of a knotted yarn or thermal effects such as relaxation would cause any interference. This novel invention thus fulfills a double function for use of the preparation agent, namely crossing and optimizing the application and distribution of the preparation agent. Due to the fact a strong conveyance effect is imparted to the air stream in the direction of yarn travel, it is possible not only to increase the yarn transport speed but also to increase the effect of the air in the sense of creating intense air eddies without producing knots. This therefore makes available for actual practice a novel element having some very positive effects that were not possible in this way in the past and it permits a variety of possible applications. In the predominant majority of application cases, air is the optimum blowing medium. However, it has been found that steam can also be used as the medium in special applications, e.g., for relaxation. This novel process step is referred to below as the migration step, and the novel air nozzle is referred to as the migration nozzle.
In POY and FOY/FDY spinning operations, the thread run is calmer with an additional migration step. There is a stabilizing effect of the thread on the downstream deflection rollers or drawing rollers, not least of all due to the more uniform distribution of spinning preparation between the filaments and thus also due to compensation of differences in thread tension. This takes place as described below, depending on the spinning operation:
In the FOY/FDY process, the thread is stabilized on the drawing rollers and the deflection rollers due to a more uniform distribution of the spinning preparation in the thread and a slight mingling of the filaments (a type of continuous intermingling without knotting). There must not be any intermingling points, because they would lead to differences in friction on the drawing rollers in the drawing operation. The migration nozzle is located upstream from the first drawing roller. If intermingling is necessary, it is performed upstream from the spooler with an additional air intermingling nozzle.
In the POY process, the goal is also stabilization of the thread on the rollers (deflection rollers here) through a more uniform distribution of spinning preparation between the filaments. The installation position is the same.
In the BCF process, individual filaments in the yarn are stabilized and the preparation is distributed. In the tricolor process, a slight color separation in the yarn is also achieved. The installation position is the same as that with the other processes.
The stream of blowing air is preferably produced with compressed air of less than 6 bar, preferably less than 1.5 bar, especially preferably from 0.3 bar to 1.2 bar. In the case of finer yarns, a pressure of approximately 0.5 bar has proven to be optimum. By means of the migration nozzle, a new method which was not known in previous practice is implemented with the crossing of the filaments. The most proximate art is intermingling. In intermingling, a blending and interconnection of the individual filaments of a yarn is sought; this can be discerned by visible knots in the product. In migration, no knots should be formed; this is achieved on the one hand by an angle of introduction of more than 15xc2x0, preferably 20xc2x0 to 60xc2x0, especially less than 45xc2x0, and on the other hand also with a lower pressure of the treatment air. Instead of forming knots, only a blending and crossing of the filaments are desired. The stream of air aimed in the direction of yarn travel has a sufficiently intense distribution and mixing function for the preparation agent in the yarn channel. The preparation agent is distributed much more uniformly over the entire yarn by means of the eddy current and the very intense movement of filaments relative to one another due to local whirling and frictional movements of the filaments, resulting in an obviously more stable thread running with a very good interconnection effect for the filaments of a yarn, even at the highest yarn conveyance speeds in effect today. The above-mentioned skipping effect was no longer detected after use of this novel invention, so that the risk of thread breakage can be reduced significantly. Treatment in the migration nozzle as part of the spinning operation preferably takes place immediately after preparation at very high yarn transport speeds.
The migration nozzle has a continuous treatment channel which widens in the direction of thread running in many applications, with a supply of compressed air aimed into the yarn channel in the direction of transport, opening into the yarn channel with a deviation of more than 15xc2x0 from a perpendicular line. The migration nozzle is arranged at a free distance directly downstream from a device for applying preparation agents. The effective yarn channel length is preferably designed so that it widens steadily, with the smallest cross section being in the area of the yarn feed and the largest cross section being in the area of the yarn draw-off from the yarn channel of the migration nozzle. Experiments so far have shown that good results are achieved when the ratio of the inlet cross section to the outlet cross section is approximately 1:2. The air feed opens approximately at the end of the first third of the treatment channel. The migration nozzle preferably has a threading slot over the length of the yarn channel, preferably arranged in the upper third of the yarn channel in the plane of separation between the nozzle plate and the baffle plate. The migration nozzle may be designed as a single nozzle, a double nozzle or a multiple nozzle.
Instead of the migration nozzle, the same nozzle or a slightly modified nozzle may also be used for relaxation, in which case steam is required instead of compressed air. Depending on the application, the nozzle may be used as a closed nozzle or as an open nozzle having a threading slot.
The inventors have recognized the fact that a nozzle with connecting means remains reliable in operation only if the nozzle can withstand pressure, heat, steam and chemicals. Not all problems encountered in practice have been solved satisfactorily with the glue joints used in the past. Glue joints can also be investigated only inasmuch as the practical connections are already known. However, the composition of a glue joint cannot be stipulated with regard to attack by as yet unknown chemicals to be used in the future, not to mention the additional effects of heat and moisture. Preferably the connecting means in the novel solution are arranged in the same alignment, preferably aligned so they are flush with the yarn travel. It has surprisingly been found with a corresponding pin connection that the entire nozzle body can be designed to be much smaller, even in miniaturized form in comparison with the state of the art. Especially in the case of use of a double nozzle or multiple nozzles side by side, the separation between two adjacent yarn runs can be selected to be much smaller than in the past. In some applications, this even has a feedback effect on the size of the godet rollers. Due to the possibility of miniaturization, additional yarn runs can be provided on the same machine size, thanks to this novel connection, and the total output of the machine can be increased accordingly. This means that the connection means which is otherwise used in clock and watch technology brings unexpected advantages in an entirely different area. The forced cohesion of the parts can be ensured by a traditional screw connection, as in the state of the art. This novel embodiment is especially advantageous in the application as an intermingling nozzle and as a thermal treatment body, and it is very advantageous when used as a migration nozzle, as will be explained below.
In agreement with the known intermingling nozzles, the treatment medium is directed at the longitudinal center axis of the yarn channel with the greatest possible accuracy, but with an inclination of more than 15xc2x0 in the yarn transport direction. This produces uniform eddies on both sides but no knots.